实体框架核心 map 相关实体仅当它不是 null

Question

I have these 2 classes, Process and Task. Task is a related entity and is optional. I want to be able to map Task properties on select only if this is not null. How do i handle it?

public class Process
{
    public int Id {get;set;}
    public string Description {get;set;}
    public int? TaskId {get;set;}
    public Task Task {get;set;}
}

public class Task
{
    public int Id {get;set;}
    public string Description {get;set;}
}

on my razor page

public PageViewModel Process {get;set;}
[BindProperty(SupportsGet = true)]
public int Id { get; set;}
public void OnGet()
{
    Process = _context.Processes
                  .Select(p => new PageViewModel
                  {
                      Id = p.Id,
                      Description = p.Description,
                      HasTask = p.TaskId.HasValue,
                      TaskDescription = p.Task.Description // How to handle if task is null here?
                  })
                  .FirstOrDefault(p => p.Id == Id)

}

public class PageViewModel
{
    public int Id{get;set;}
    public string Description {get;set;}
    public bool HasTask {get;set;}
    public string TaskDescription {get;set;}
}

Answer 1

p.Task == null? "": p.Task.Description

Answer 2

TaskDescription = p.Task?.Description

The code above will set TaskDescription to null if Task is null.